The present invention relates to a reflector and an antenna system, in particular to a reflector and an antenna system arranged to transmit and/or receive radiation of two frequency bands. Such a reflector or antenna system may be used within a seeker system of a missile.
According to EP1362385, a missile seeker arrangement can include a Cassegrain antenna system mounted within the radome of the missile. Such a Cassegrain antenna incorporates a parabolic shaped primary reflector and a hyperbolic shaped secondary reflector.
The secondary reflector is mounted to the primary reflector via a support. The support is made from a dielectric material having a thickness selected to minimise transmission loss.
The primary reflector is mounted on a gimbal arrangement so as to be articulated about either roll or pitch axes with respect to the missile. In this manner a greater field of view can be provided for the seeker arrangement.
The secondary reflector is formed from a mirror surface and is designed to reflect radiation incident thereon to either the primary reflector for transmission or to reflect radiation received from the primary reflector to a receiver or detector section via a focusing lens.
The missile seeker arrangement is arranged to receive and/or transmit both radio frequency and infra-red frequency bands simultaneously to make optimum use of the finite aperture available. Such a system is known as a dual mode radar seeker.
One problem introduced when a Cassegrain antenna is used within such a dual mode seeker is that complicated optical design and components are required in order to correct aberrations induced on the infra-red frequency band by components associated with the radio frequency band.